It depends a lot if you are building a show truck or just want a casual driver. Back in the 50's and 60's we used to take the main leaf and put it in a hydraulic press and press the leaf between two blocks every few inches until we got the desired arch. It would last for several years of driving over rough country roads. Spring shops can re arch them or you can buy them at Eaton Spring. It all depends on how much money you want to spend. http://www.eatonsprings.com/